Methods and apparatus for processing yarn



March 19, 1963 N. E. KLElN ETAL 3,081,510

METHODS AND APPARATUS FOR PROCESSING YARN Filed July 8, 1955 4Sheets-Sheet l INVENTORS NORMAN E. KLEIN F56. -E-

ATTORNEY March 19, 1963 N. E. KLEIN ETAL METHODS AND APPARATUS FORPROCESSING YARN 4 Sheets-Sheet 2 Filed July 8, 1955 FIG. -2-

INVENTORS NORMAN E KLEI N FRANK E. ROWE,JR. BY M ATTORNEY March 19, 1963N. E. KLEIN ETAL 3,081,510

METHODS AND APPARATUS FOR PROCESSING YARN Filed July 8, 1955 4Sheets-Sheet 5 JNVENTORS NORMAN E. KLEIN ATTORNEY FRANK E. ROWE,JR.

March 19, 1963 N. E. KLEIN ETAL 3,081,510

METHODS AND APPARATUS FOR PROCESSING YARN Filed July 8, 1955 4SheetsSheet 4 IN VEN TORS ATTORNEY NORMAN E. KLEIKN FRANK E. ROWE JR.

United States Patent 3,081,510 METHODS AND APPARATUS FUR PROCESSING YARNNorman E. Klein, Pendleton, and Frank E. Rowe, In, Clemson, S.C.,assignors to Deering Millilren Research Corporation, Pendleton, S.C., acorporation of Delaware Filed July 8, 1955, Ser. No. 520,838 (Ilaims.(Cl. 281) This invention relates to improved methods and apparatus forperforming processing operations upon a running length of yarn. In itsmore specific aspects the invention relates to improvements in processesfor manufacturing crinkled or coiled yarns having an elastic nature asdisclosed in co-pending US. application, Serial No. 274,358, filed March1, 1952, and to apparatus for performing the improved processes.

The above identified co-pending application discloses a process formaking crinkled or coiled yarn which process comprises subjecting theyarn to heating conditions and thereafter passing the hot yarn under lowtension through a very sharp angle. The application also disclosessuitable apparatus for preparing the yarn which apparatus comprises aflattened heater strip over which the yarn is passed at an elevatedtemperature and a blade member having an acuate edge positioned in closeproximity to the heater strip so that the hot yarn can be passed overthe acuate edge to cause the yarn to follow an angular path. While theapparatus disclosed in the above identified co-pending application iscapable of producing an excellently elasticized yarn, the apparatusnevertheless leaves room for improvement in several respects.

A first disadvantage of the earlier apparatus is that the flattenedstrip of metal employed for heating the yarn has a very high heat losseven though insulation is employed where feasible to cover portions ofthe heater strip. The heat loss is appreciable even when very slow yarnspeeds are employed and with higher yarn velocities, which requirecorrespondingly wider heater plates, the heat loss reaches the pointwhere it is a major source of expense. Not only is a high heat lossobjectionable and expensive because of the excessive energy required tomaintain the heater strip at a proper temperature, but the heat which islost must be removed from the room or building in which the machine isoperating and this places a greatly increased load on the airconditioning equipment. In fact, with recently designed, high speedapparatus constructed according to the disclosure of the above mentionedapplication, the cost of energy for heating the heater strip and thecost of additional air conditioning constitute a major portion of thetotal expense of processing the yarn.

A second disadvantage of the earlier apparatus is that it provides noconvenient means for varying the amount of tension imparted to the yarnby contact with the heater element. In certain instances it is extremelydesirable that contact of the yarn with the heater strip impart anappreciable tension to the yarn while in other instances it is desirablethat very little tension be imparted to the yarn by its contact with theheating element. As will readily be seen, a flat plate in contact withthe yarn provides no means for readily varying the tension imparted tothe yarn by its contact with the plate as long as the size of the plateremains constant.

Still another disadvantage of the earlier apparatus is that in someinstances low denier yarns cannot be supplied to the heater strip undera low enough tension to permit adequate contact for the desired degreeof heating without having the yarn under an excessively high tension atthe time it contacts the senate edge. Accordice ing to the process ofthe above identified application, th tension in the yarn after passageabout the acuate edge need only be about 0.2 gm. or less per denier andwith yarns of very low denier, this results in a total tension of only afew grams. It is, therefore, necessary that such yarns be supplied tothe heater element under a practically negligible tension since contactwith the heating element will increase the tension of the yarn and ifthe tension is appreciable immediately preceding the point at which theyarn contacts the heater element, it becomes impossible to retain thetension in the yarn at the desired level following its contact withheater plate.

Still another disadvantage of the earlier apparatus is that it providesinadequate tension regulation in some instances and in particular whenyarns of very low deniers are being processed. The difiiculties ofsupplying a yarn end under a very low but constant tension will beapparent to those skilled in the art and yet any variation in tension inthe yarn being supplied results in large diiferences in the degree ofelastization of the finished yarn. A non-uniformly elasticized yarn isnot only objectionable because of its lower average degree of elasticitybut also because it tends to result in woven or knitted goods having anon-uniform appearance.

It is a primary object of this invention to provide apparatus, suitablefor processing yarn according to the method disclosed in US. applicationSerial No. 274,358, which overcomes the disadvantages of earlierapparatus.

It is another object of the invention to provide apparatus, useful inthe production of elasticized yarns, which is extremely simple indesign, which is inexpensive to manufacture and which is economical inoperation.

It is still another object of the invention to provide improved methodsfor maintaining a running length of yarn under a substantially constanttension during such time that a processing operation is performed on theyarn.

The above as well as other objects of the invention are accomplished bythe provision of apparatus which utilizes a heater element in the formof an elongated rod about and along which the yarn may be passed for atotal of about /2 or more turns to thereby result in adequate contactand uniform heating. A. blade member is preferably secured generallytransversely of the longitudinal axis of the rod heating element withits acuate edge positioned in close proximity to the surface of the rodso that a yarn end in contact with the heating element can be drawn intocontact with the acuate edge without any appreciable drop in thetemperature of the yarn. Preferably the apparatus also includes anoverfeed, i.e., metering device for feeding a greater length of the yarnto the heater rod than is withdrawn from the acuate edge so that theyarn is allowed to contract while in contactwith the heater element.

Preferred embodiments of the invention will now be illustrated withreference to the accompanying drawings in which:

FIGURE 1 is a front plan view of one form of apparatus according to theinvention showing two positions for independently processing two ends ofyarn.

FIGURE 2 is a cross-sectional view of the apparatus of FIGURE 1 takenalong line 2--2 in FIGURE 1.

FIGURE 3 is a schematic drawing of the gear arrangement for the overfeeddevice of FIGURE 1.

FIGURE 4 is a schematic drawing of the apparatus of FIGURE 1illustrating the yarn ficw path and the electrical circuit for theheater element.

FIGURE 5 is an enlarged view in perspective of one of the bracketmembers which serves as a support for the blade member.

FIGURE 6 is an enlarged view of a modified form of heater rod.

With reference to FIGURES 1 to 5 of the drawings in greater detail,there is illustrated a support frame, generally indicated by thereference numeral 10, having a first horizontally extending supportmember 11 carrying a plurality of supply bobbins 12, to supply an end ofyarn to each of the positions of the yarn elastrcizrng apparatus. An endof yarn 13 from each of the bobbins 12 is drawn through a guide member14, positioned axially of the supply bobbin so that the yarn may bereadily removed in an over-end manner, and is thereafter passed to atensioning device, generally indicated by the reference numeral 15,which is secured to a frame member 16 by any suitable means. Thetensioning device may be and preferably is a gate type tensionregulating device such as disclosed in US. patent application Serial No.469,430, filed November 17, 1954, now US. Fatent 2,790,611, since, aswill subsequently be explained in detail, the use of an eflicientregulating device permits the apparatus to be employed with moredifferent types of yarn; however, for most types of yarn, the tensioningdevice 15 may be of any conventional type since it ordinarily serves thesole purpose of pretensioning the yarn to a slight extent as it is fedto the elasticizing apparatus.

The reference numeral 17 generally indicates an overfeed arrangementwhich permits the yarn to contract a selected amount during theelasticizing procedure. The overfeed arrangement comprises a housing 18having a support portion 19 secured to a frame member 20 by any suitablemeans such as by bolt 21. Extending through housing 18 and journaled insuitable bearings, not illustrated, is a rotatable shaft 22 and carriedby the shaft 22 within housing 18 is a small spur gear 23. Gear 23drives an idler gear 24 which in turn drives a larger gear 25 carried bya shaft 27 which also passes through housing 18 and extends outwardly oneither side thereof. Gear 25 drives a small idler gear 28 which mesheswith a spur gear 29 carried by a third shaft 30 which is journaled inthe walls of housing 1 8 and extends from the housing on one sidethereof. A cylindrical roll 31 having a smooth yarn engaging surface issecured to one end of shaft 27 and, in cooperation with a small roll 32secured to shaft 39, serves to withdraw the yarn in a manner to besubsequently described. Roll 31 is of larger diameter than roll 32 butthe gear ratio is such that the smaller roll is driven at a suflicientlyhigher number of revolutions per minute to give the rolls asubstantially equal peripheral velocity. Mounted on shaft 27 on theopposite end to roll 31 is a yarn engaging over-feed roll 33 whichrotates at the same r.p.m. as roll 31 but which preferably has a largerdiameter than roll 31 to give it a higher peripheral velocity.

The housing 18 is provided with an upstanding triangular flange 34 whichcarries a pair of small pigtail guides indicated by the referencenumerals 35 and 37. Extending into housing 18 through flange 34 is amotion transfer rod 38 which is operatively connected to a clutch, notillustrated, which makes it possible to disengage gear 23 from gear 24for purposes of starting and stopping each individual position.Extending upwardly from housing 18 and carried thereby is a support arm39 carrying a small idler pulley 40 which acts as a guide in a manner tobe subsequently described.

From the above description of the overfeed mechanism, it will beapparent to those skilled in the art that this component of theapparatus can readily be constructed from the yarn feed deviceconventionally employed on an Atwood Model 10-13 twister frame sold bythe Universal Winding Company. The only necessary modifications are alengthening of shaft 27, the addition of overfeed pulley or roll 33 andthe addition of pigtail guide 35. In fact, as will subsequently becomeapparent, the entire apparatus can readily be made by modification of anAtwood l0-B twister frame.

Carried by frame member 16 and extending generally transversely of thelongitudinal axis thereof are a pair of support members 41, only one ofwhich is illustrated.

Extending through suitable bores in support members 41 and insulatedtherefrom is a heater rod 42 having any suitable diameter, for examplefrom to /2 inch, and which is preferably formed of an alloy, such asthat sold under the name of Nichrome, having a relatively highelectrical resistance. The heater rod 42 is illustrated as extendingacross only two positions but it can suitably be of such length as totraverse one entire side of a twister frame and its small area, ascompared to that of a wide flat strip, results in a very low heat loss.A compression spring member 43 is mounted over one end of the resistancerod 42 and has one end positioned against frame member 41 and theopposite end against an electrically non-conducting washer member 44made of any suitable material such as resin impregnated fabric. Thespring 43 is compressed by a nut 45, bearing against washer 44, which isin threadwise engagement with the extremity of heater element 42. Thisarrangement serves to tension the heater rod 42 and permits it to expandupon being heated without allowing it to sag under the force of gravity.

One end of heater rod 42 is electrically connected through a suitableconductor 47 to a step-down transformer illustrated schematically andindicated by reference numeral 48. Transformer 48 should be designed tosupply power to rod 42 at a voltage sufliciently low, for example belowabout 30 volts, that the rod does not provide a shock hazard.Transformer 48 is operatively connected by means of conductors 49 to avariable transformer 56 which in turn is connected to a suitable supplyof electrical power through a switch 51 and conductors 52. The end ofheater rod 42 opposite to that connected to transformer 48 may beelectrically grounded, for example to frame member 41, if one terminalof the transformer 48 is likewise grounded, as illustrated at 53, tothereby complete the electrical circuit.

Carried by frame member 16 are a plurality of support brackets 60 andsecured to each of the brackets 60 is a small plate 61 with a suitablebore '62 for the passage therethrough of the heater rod 42. Brackets 61can suitably be made of any rigid material such as metal but plates 61are preferably made of an electrically nonconducting material, such as aresin impregnated fabric, so as not to short circuit the heater rod bycontact therewith. Extending from brackets 60, in each instance, is anelongated arm 63 having an arcuate insert 64 made of a wear resistantmaterial such as porcelain (see FIG- URE 5 of the drawings). The arcuateinsert 64 preferably has a radius of curvature which approximatelycorresponds to the periphery of heater rod 42 and is positioned closelyadjacent thereto to guide a yarn end traveling from over-feed roll 33into contact with the heater element. Also carried by brackets 60, ineach instance, is a small support arm 65, carrying a guide pulleyindicated by the reference numeral 67, and still another arm 68 whichserves as a support for a flattened blade member 69 having an acuateedge positioned closely adjacent to the heater rod. The blade member 69is preferably adjustably secured to arm 68 so that the distance of theacuate edge from the heater rod can be adjusted to give the mostsatisfactory results.

Means 76 is provided for collecting the yarn and is illustratedschematically in FIGURE 4 of the drawings as constituting a conventionalring and traveller arrangement. It will be understood, however, that anyconventional yarn take-up device can be used and that it is notnecessary that a device be employed which results in the yarn beingtwisted. In fact, in many instances twisting of the yarn is not desiredand, of course, in such instances a ring and traveller take-up deviceshould not be employed.

For edge-elasticizing, the apparatus can be threaded in two slightlydifferent ways. For yarns which contract on heating, a yarn end fromsupply 12 is fed through guide 14 and tension regulating means 15 and.is there after passed to roll 33 of the overfeed device 17. The yarn endis wrapped approximately 1 /2 turns around feed roll 33 and is thenpassed to the arcuate insert in arm 63. The yarn is then wrapped /2 ormore turns around heater rod 42 and is passed to the blade member 69carried by the bracket member 60 positioned immediately to the right ofthe bracket member supporting the arm 63 over which the yarn is passed.(See FIGURE 4.) The brackets 60 should be so placed that the distancebetween the arm 63 on one bracket and the blade 69 on an adjacentbracket is at least sufiicient to result in the yarn being adequatelyheated without requiring a rod with an excessively large cross-sectionand should generally not be less than 1 or 2 inches. On the other hand,there is generally no advantage in making this distance greater thanabout 20 inches unless yarns of a very large size are being prowssed.The number of turns that the yarn is wrapped around the heater roddepends entirely upon the amount of tension that is to be imparted tothe yarn by its contact with the heater element, as will subsequently beexplained in greater detail.

When employing the yarn crimping aspect of the invention, the yarn ispassed about the acuate edge of the blade 69 following its contact withthe heater element and is then passed generally parallel to the heaterelement to the guide pulley 67 carried by the same bracket 60 thatsupports the arcuate inset over which the yarn is passed. The yarn endis then passed through guide 37 and wrapped a number of turns aboutrolls 31 and 32 which serve to withdraw the yarn at a constant rate withrespect to the rate of feed. The yarn end is thereafter passed aboutpulley 40 to takeup means 70, and the temperature of the heater elementis brought to a proper value by adjustment of transformer 50. Theapparatus is then placed in operation.

The arrangement described in the preceding paragraph is suitable for useonly with conventional, -i.e., drawn yarns, such as nylon, whichcontract on heating since as will be readily apparent to those skilledin the art, if the yarn does not contract on heating the overfeedarrangement will result in a surplus of yarn which will prevent theapparatus from operating properly. With yarns that do contract onheating, however, the overfeed arrangement provides excellent tensioncontrol. The tension in the yarn before it reaches the feed roll 33 willnormally fluctuate because the resistance met in unwinding the yarn fromthe supply package will vary but these fluctuations will be eliminatedby the overfeed roll and the only tension in the yarn immediatelyfollowing its passage around the overfeed roll is present as a result ofthe contraction of the yarn under the influence of heat. Inasmuch as ithas been found that the tension due to contraction of the yarn remainsrelatively constant even with slight variations in the temperature towhich the yarn is heated, it will be seen that the ov-erfeed arrangementpermits extremely low but uniform tensions which are outside the rangeordinarily obtainable with conventional tension regulating devices.

Best results with the overfeed arrangement are generally achieved whenthe diameter of feed roll 33, as compared with the diameter ofwithdrawing roll 31, is such as to give the maximum overfeed which canbe achieved without the yarn becoming slack. This permits the yarn tocontract the maximum possible extent on the side thereof contacted bythe edge 69 and it has been found that this results in a higher degreeof elastization than can otherwise be achieved, although it will readilybe seen that the yarn can be caused to undergo any desired degree ofthermal contraction by the employment of this overfeed shrinkingarrangement. If overfeediug the yarn results in it reaching the blade atan undesirably low tension, it is generally preferable that the tensionin the yarn at this point be increased by increasing the number of turnswith which the yarn is wrapped around the heater rod rather than bydecreasing the degree of overfeed. Of

course, the degree that the yarn can be overfed Without becoming slackwill vary with different types of yarn but almost any type of yarn canbe accommodated by changing the size of the feed roll 33 and it. hasbeen found that a range of rolls sufiicient to give an overfeed of fromabout l to 15% is generally adeq uate. For any selected type of yarn onecan attempt to operate with the largest roll and if the yarn refuses torun, can gradually decrease the size of the roll until one is found thatis satisfactory. As a guide, it has been found that with Du Pont nylontype 200 (polyhexamethylene adiparnide) yarns an overfeed of about 10.0%generally gives the best results.

In view of the above description of the overfeed arrangement, it will beseen that it is advantageous for use with any yarn which contracts onheating, since it not only permits the yarn to be fed to the heaterelement under a uniformly low tension so that the yarn is permitted tocontract the maximum amount possible, but also permits the tension inthe yarn as it passes over the acuate edge to be readily adjusted byincreasing or decreasing the frictional contact of the yarn with theheater element. The arrangement is, however, particularly advantageousfor use with yarns of very small denier, since the tension that must bemaintained in these yarns for best results is extremely low even aftercontact of the yarn with the acuate edge and this makes an uniformly lowtension in the yarn before it contacts the heater element, not onlyadvantageous but absolutely necessary. By the overfeed arrangement, asdescribed above, the tension in the yarn prior to its contact with theheater element can be too small to be accurately measured and yet can beretained at a very uniform value as is evident from the quality of theyarn produced.

With yarns that do not readily contract on heating, the positive yarnoverfeed arrangement in which the yarn is positively metered to theheating zone at a rate in excess of that at which it is withdrawn is notgenerally advantageous although it can sometimes be employed byadjusting the rate of feed to exactly equal or to be slightly less thanthe rate of withdrawal. For use with this type of yarns, however, theapparatus is preferably threaded by passing the yarn end from tensionregulator 15 through guide 35 and to the arcuate inset in arm 63, withthe remainder of the yarn path the same as previously described. By thisarrangement the tension in the yarn being fed to the heater element iscontrolled by the tension regulating means 15 rather than by thecombination of positive feed and heat, and it will be apparent that theversatility of the apparatus is increased by equipping the same witheflicient tension regulating devices so that the apparatus can beemployed without utilizing the positive feed device if so desired.

With reference to FIGURE 6 of the drawings, there is illustrated amodified form of heater rod 42' which may be substituted for the heaterrod 42 in FIGURE 1 and which is designed to facilitate the threading-upoperation. A guide arm 64' is positioned in close proximity to theperiphery of the rod 42' to guide a yarn end into contact with thesurface of the rod, and spaced a suitable distance from arm 64 is ablade member 69' having an acuate edge which is also placed in closeproximity to the periphery of the heater rod. Carried by rod 42'intermediate arm 64' and blade 69 is a rotatable sleeve which ispreferably of the split type so that it may be seated within a suitableperipheral groove in rod 42' with its outer surface flush with thesurface of the heater rod. The sleeve 75 frictionally engages the heaterrod 42 with sufficient force to prevent accidental rotation thereof butwith insuificient force to prevent it from being rota-ted when desired.Extending in a substantially radial manner from sleeve 75 are aplurality of short pins 76 which have a polished surface suitable forengaging an end of yarn. In threading, it is not necessary that the yarnbe passed by hand around the heater rod but rather the yarn en-d may beled from arm 64, placed about one of the pins 76 and thereafter ledabout blade member 69. To adjust the tension imparted to the yarn by itsfrictional contact with the heater rod 42, it is then only necessary torotate sleeve 75 to thereby increase or decrease the total are throughwhich the yarn end is in contact with the surface of the heater rod. Itwill be understood that contact of the yarn with pin 76- also tensionsthe same to some extent so that the yarn need be in contact with theheater rod through a smaller total are than in the embodiment firstdescribed in order for a given amount of tension to be imparted.

Having thus described our invention, what we desire to claim and secureby Letters Patent is:

1. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, a yarn takeup means, an elongatedheater rod positioned in the yarn path, means providing an acuate edgepositioned in close proximity to the periphery of said heater rod, andmeans to positively meter said yarn to the heating means at a rate whichis constant with respect to the rate at which it is collected by saidtakeup means, whereby when an end of yarn is passed in contact with saidrod and withdrawn over said acuate edge, the uniformity of the tensionin the yarn as it passes in contact with the acuate edge can be efiectedby the combined action of positively metering and heating the yarn, andthe magnitude of the tension in the yarn as it passes in contact withsaid acuate edge can be readily regulated by changing the total arethrough which said yarn is in contact with the peripheral surface ofsaid heater rod.

2. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, a yarn takeup means, an elongatedheater rod, guide means to guide said yarn into contact with said rod, ablade mem ber having an acuate edge extending generally transversely ofthe longitudinal axis of said rod, said blade member being so positionedthat said acuate edge is in close proximity to the periphery of said rodat a point spaced from that at which the yarn is guided into contactwith the rod by said guide means to thereby permit said yarn to bewrapped a total of at least about /2 turn about said rod and withdrawnover said acuate edge, means to positively meter said yarn into contactwith said heater rod at a rate in excess of that at which it iscollected by said takeup means, whereby the uniformity of the tension inthe yarn as it passes in contact with the acuate edge is insured by thecombined action of overfeeding the yarn and heating the same and themagnitude of the tension of the yarn as it passes in contact with theacuate edge may be readily regulated by changing the total are throughwhich said yarn is in contact with the peripheral surface of said heaterrod.

3. Apparatus according to claim 2 wherein said heater rod is of agenerally cylindrical shape and has a diam eter of from about & to /2inch.

4. Apparatus according to claim 2 including pre-tensioning means toplace the yarn under tension as it is fed to the positive meter means.

5. Apparatus according to claim 4 wherein said pretensioning meanscomprises a gate type tension regulator.

6. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, a yarn takeup means, an elongatedheater rod positioned in the path of a yarn end being passed from saidsupply means to said takeup means, blade means having an acuate edgepositioned in close proximity to the periphery of said heater rod,whereby when an end of yarn is passed in contact with said rod andwithdrawn over said acuate edge, the tension in the yarn in contact withsaid edge can readily be varied by changing the number of turns of saidyarn about said rod.

7. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, a yarn takeup means, an elongatedheater rod positioned in the path of a yarn end passing from said supplymeans to said takeup means, yarn guide means to guide said yarn end intocontact with said heater rod, blade means having an acuate edgepositioned in close proximity to the periphcry of said heater rod at apoint spaced from said guide means, a rotatable sleeve positioned aboutsaid heater rod at a point intermediate said guide means and said blademeans, said sleeve carrying at least one pin member, whereby when an endof yarn is passed in contact with the said rod and withdrawn over saidacuate edge, said sleeve member can be rotated to cause said pin memberto engage said yarn and vary the arc through which said yarn engages theperipheral surface of said heater rod.

8. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, a yarn takeup means, an elongatedheater rod, guide means to guide said yarn into contact with said rod, ablade member having an acuate edge extending generally transversely ofthe longitudinal axis of said rod, said blade member being so positionedthat said acuate edge is in close proximity to the periphery of saidheater rod at a point spaced from that at which the yarn is guidedintocontact with said heater rod by said guide means to thereby permit saidyarn to be wrapped a total of at least about /2 turn about said rod andwithdrawn over said acuate edge.

9. Apparatus according to claim 8 wherein said rod has a generallycylindrical shape and a diameter of about to /2 inch.

10. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, a yarn takeup means, means to heat saidyarn at one point in its linear path, means providing an acuate edgeover which the heated yarn is drawn, and means to positively meter saidyarn to the heating means at a rate in excess of that at which it iscollected by said takeup means, whereby the combined action of thepositive meter means and said heating means serves to uniformly tensionthe yarn.

11. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, means to heat said yarn at one point inits linear path, means providing an acuate edge, means for positivelyWithdrawing said yarn from said heating means over said acuate edge,means for positively metering said yarn to said heater means at a ratein excess of that at which it is withdrawn by the Withdrawing means,whereby the yarn is allowed to contract upon being heated and thetension in the yarn is maintained at a uniform level by the combinedaction of overfeeding the yarn and heating the same.

12. Apparatus for processing a running length of yarn comprising incombination a yarn supply means, a yarn takeup means, an elongatedcylindrical heating rod, a first bracket means, said first bracket meanscarrying a support arm having an arcuate, abrasion resistant insertpositioned in closed proximity to the periphery of said rod, saidabrasion resistant insert having a curvature substantially correspondingto the curvature of the periphery of said rod so that a yarn end passedover said insert is guided into contact with said heater rod, a secondbracket means carrying a blade member with an acuate edge positionedgenerally transversely of the longitudinal axis of said heater rod andin close proximity to the periphery of said rod at a point spaced alongthe longitudinal axis of said rod from that at which the yarn is guidedinto contact with the rod by said arcuate insert to thereby permit theyarn to be wrapped at least about /2 turn about said rod and withdrawnover said acuate edge, a first driven roll to positively meter the yarninto contact with said heater rod, a second driven roll to positivelywithdraw the yarn from said heater rod over said acuate edge at a rateless than that at which it is fed to said heater rod by said first roll,and pre-tensioning means to tension the yarn prior to its being passedto said first roll, whereby the uniiormity or" the tension in the yarnas it passes in contact with the acuate edge is insured by the combinedaction of overteeding the yarn and heating the same and the magnitude ofthe tension in the yarn as it passes in contact with the senate edge maybe readily varied by changing the number of turns of said yarns aboutsaid heater rod.

13. Improved apparatus for heating and controlling the tension in arunning length of yarn as it is passed under tension about a sharp edgeof a blade member in an acutely angular path, said improved apparatuscomprising, in combination, an elongated heater rod, guide means toguide an end of yarn into contact with said rod, and blade holding meansfor securing a blade member so that a sharp edge of said blade memberextends generally transversely of the longitudinal axis of said rod andis positioned adjacent the periphery of said rod at a point spacedaxially of said rod from that at which the yarn is operatively broughtinto contact with said red by said guide means.

14. Improved apparatus for controlling the tension in a running lengthof heat-contractible yarn as it is passed under tension to a yarn heaterand immediately thereafter about a sharp edge of a blade member in anacutely angular path, said improved apparatus comprising, incombination, means to positively meter, at a selected linear rate, anend of said yarn to said yarn heater and means to positively withdraw,at a second selected linear rate that is less than said first rate, saidend of yarn from said blade edge, whereby the rate of metering of saidyarn to said heater and the rate of withdrawal of said yarn from saidblade edge may, with respect to the temperature to which the yarn isheated, be correlated to provide, as a result of yarn contraction, asubstantially constant tension in said yarn as it passes about saidblade edge.

15. Improved apparatus for controlling the tension in a running lengthof heat-contractible yarn as it is passed under tension to a yarn heaterand immediately thereafter about a sharp edge of a blade member in anacutely angular path, said improved apparatus comprising, incombination, a first yarn advancing means, including an over-feed roll,to deliver an end of yarn to said yarn heater, a second yarn advancingmeans, including at least one driven roll, to withdraw an end of yarnfrom said blade edge, and means to drive said over-feed roll and saidsecond named roll such that the peripheral surface of said over-feedroll moves at a rate in excess of the rate of movement of the peripheralsurface of said second named roll, whereby an end of yarn passing fromsaid over-drive roll to said yarn heater and thereafter to said secondnamed roll is permitted to contract under the influence of heat and canbe maintained under a substantially constant tension as a result ofcontraction.

;16. Apparatus according to claim wherein said over-drive roll and saidsecond named roll are secured to a single drive shaft and thecircumference of said over- 1Q drive roll is from about 1 to 15% greaterthan the circumference of said second named roll.

17. An improved method for controlling the tension in a running lengthof a heat-contraotible yarn in an elasticizing operation which includesthe steps of heating the yarn and immediately thereafter passing the hotyarn about a sharp edge of a blade member, said method comprisingpositively metering said yarn at a selected linear rate to the area inwhich it is heated and positively withdrawing said yarn from said areaat a second selected linear rate which is less than the rate at whichthe yarn is metered to said area, the values for said first and secondlinear rates being such that the yarn in said area of heating ismaintained, as a result of contraction, under a substantially constanttension.

18. A method according to claim 17 wherein the rate at which the yarn ismetered to said area in which it is heated is about 1 to 15% greaterthan the rate at which the yarn is withdrawn from said area.

19. In a method for elasticizing a polyhexamethylene adipamide yarnhaving a potential contraction under the influence of heat of at leastabout 10%, said method including the steps of passing a running lengthof said yarn, under tension, in an acutely angular path about the sharpedge of a blade member and heating the yarn in a portion of the yarnpath immediately preceding the portion of the yarn path in which saidyarn passes about said edge, the improvement which comprises positivelymetering said yarn to the area of heating at a selected linear rate, andpositively withdrawing said yarn from said area and about said edge at alinear rate less, but not more than about 10% less, than the rate atwhich it is fed to said area, whereby the yarn is retained under tensionas it passes about said edge solely as a result of contraction.

20. A method for heat-treating nylon yarn which comprises positivelymetering a heat-contractible drawn nylon yarn through a processing zoneat a first selected linear rate, positively metering said yarn from saidprocessing zone at a second linear rate which is less than said firstrate so as to provide a degree of overfeed less than that which causessaid yarn to become slack when heated, dry heating said yarn bycontacting said linearly progressing yarn with a conductive heatingsurface within said processing zone to a temperature to result incontraction of said yarn, and correlating the rate at which said yarn ismetered to said zone, the rate at which said yarn is metered from saidzone and the temperature to which said yarn is heated to thereby permitsaid yarn to contract at a low and uniform tension within saidprocessing zone.

References Cited in the file of this patent UNITED STATES PATENTS1,882,539 Anderson Oct. 11, ,1932 2,111,211 Finlayson et al. Mar. 15,1938 2,204,603 Kline et al. June 18, 1940 2,345,032 Castricum Mar. 28,1944 2,584,779 Averns et a1 Feb. 5, 19,52

1. APPARATUS FOR PROCESSING A RUNNING LENGTH OF YARN COMPRISING INCOMBINATION A YARN SUPPLY MEANS, A YARN TAKEUP MEANS, AN ELONGATEDHEATER ROD POSITIONED IN THE YARN PATH, MEANS PROVIDING AN ACUATE EDGEPOSITIONED IN CLOSE PROXIMITY TO THE PERIPHERY OF SAID HEATER ROD, ANDMEANS TO POSITIVELY METER SAID YARN TO THE HEATING MEANS AT A RATE WHICHIS CONSTANT WITH RESPECT TO THE RATE AT WHICH IT IS COLLECTED BY SAIDTAKEUP MEANS, WHEREBY WHEN AN END OF YARN IS PASSED IN CONTACT WITH SAIDROD AND WITHDRAWN OVER SAID ACUATE EDGE, THE UNIFORMITY OF THE TENSIONIN THE YARN AS IT PASSES IN CONTACT WITH THE ACTUATE EDGE CAN BEEFFECTED BY THE COMBINED ACTION OF POSITIVELY METERING AND HEATING THEYARN, AND THE MAGNITUDE OF THE TENSION IN THE YARN AS IT PASSES INCONTACT WITH SAID ACUATE EDGE CAN BE READILY REGULATED BY CHANGING THETOTAL ARC